1. Field of the Invention
The present invention relates to substrate treating methods and apparatus for use in modifying films formed on substrates such as semiconductor wafers. More particularly, the invention relates to a technique of heating substrates in an atmosphere including the vapor of a treating liquid or solution.
2. Description of the Related Art
An outline of a conventional substrate treating apparatus of this type will be described with reference to FIG. 1.
This substrate treating apparatus includes a vaporizer 10 for vaporizing a treating liquid, and a treating chamber 20 for treating substrate or wafer W in the vapor of the treating liquid supplied from the vaporizer 10.
The vaporizer 10 has a bubbling tank 11 for storing the treating liquid which is heated by a heater 12 provided for the bubbling tank 11. A gas feed pipe 13 extends into the bubbling tank 11 for mixing a carrier gas such as nitrogen gas into the treating liquid. A vapor transmitting pipe 14 extends from an upper position of the bubbling tank 11. The vapor of the treating liquid generated by heating is transmitted along with the carrier gas through the vapor transmitting pipe 14 to the treating chamber 20.
The treating chamber 20 includes a substrate support table 21 for supporting a substrate such as a semiconductor wafer W under treatment, and an open/close main body 22 disposed over the support table 21. The support table 21 has a heater 23 embedded therein for heating the wafer W, and a lift mechanism 24 for raising and lowering the wafer W. The lift mechanism 24 includes a plurality of support pins 25 for supporting the wafer W, and an air cylinder 26 for raising and lowering the support pins 25. The vapor transmitting pipe 14 is connected to an upper position of the main body 22 to introduce the vapor of the treating liquid into a treating space 27 defined by the main body 24.
The conventional substrate treating apparatus noted above is operable for treatment of wafer W as follows.
With the main body 22 retracted upward to open the treating space 27, the wafer W is brought in and placed on the support pins 25 projecting from the support table 21. Subsequently, the main body 22 is lowered to close the treating space 27 tight. As the vapor of the treating liquid is introduced from the vaporizer 10 into the treating space 27, the support pins 25 are lowered to place the wafer W on the support table 21. The wafer W is treated in a vaporous atmosphere of the treating liquid while being heated by the support table 21.
The above conventional substrate treating apparatus has the following drawback.
When the vapor of the treating liquid is introduced into the treating space 27, the wafer W is in a position away from the support table 21, and is therefore below a heating temperature set to the support table 21. As a result, the temperature of the wafer W is lower than the temperature of the vapor of the treating liquid introduced into the treating space 27. The vapor of the treating liquid introduced into the treating space 27 is cooled adjacent the wafer W and condenses on the wafer W. The condensation degrades the film formed on the surface of wafer W under treatment.
To overcome such an inconvenience, the wafer W may be placed and heated on the support table 21 prior to introduction into the treating space 27 of the vapor of the treating liquid. In the case of treatment conducted in such a sequence, the film formed on the wafer W would temporarily be heated in an atmosphere not including the vapor of the treating liquid. Certain types of film require treatment in the vapor of the treating liquid in order to avoid dispersion of components contained in the film. The treatment conducted in the above sequence would disperse the components from the film, resulting in a different problem of deteriorating the film.